1. Field of the Invention
The present invention relates to a method of producing a solid body having depressed portions on its surface, and to a method of producing an electrophotographic photosensitive member.
2. Description of the Related Art
Recently, in a variety of industrial fields, attention has been paid to the shape of solid body surfaces, and research is being conducted. Japanese Patent Application Laid-Open Nos. 2001-157574 and 2002-335949 disclose a method of producing a porous body having a honeycomb structure by casting a hydrophobic organic solvent solution of a biodegradable, amphiphilic polymer to bedew the cast solution surface. This porous body is expected to be used in a medical field. Further, Japanese Patent No. 4018741discloses a method of producing a solid body having a varied surface shape by combining a hydrophilic solvent and a hydrophobic solvent under specific conditions. This solid body is expected to be used in a wide range of fields. In addition, Japanese Patent Application Laid-Open Nos. 2008-179749 and 2008-203807 disclose a method of producing a solid body having depressed portions on a surface. 
However, with the methods disclosed in Japanese Patent Application Laid-Open Nos. 2001-157574 and 2002-335949, in order to bedew the cast solution surface, a special amphiphilic polymer is required and the surrounding environment should be controlled. Especially in the case of blowing a high-humidity gas or air, there is a possibility that the surface of a cast film may be disrupted, and there is a problem in that the production conditions and apparatus are greatly restricted.
Further, in the method disclosed in Japanese Patent No. 4018741, there is room for further improvement in terms of productivity, selectivity of polymer compound, and the controllability of depressed portions.